DE 10 2005 018 956 A1 or DE 102 48 355 A1 has disclosed an electric camshaft adjuster of an internal combustion engine. The camshaft is driven at half speed from the crankshaft, to which end a camshaft drive gear of the camshaft is coupled to the crankshaft. An adjusting mechanism between the camshaft and the camshaft drive gear permits an adjustment of the phase position of the camshaft drive gear and the camshaft. The adjusting mechanism can be configured, for example, as a double planetary gear mechanism or as a harmonic drive mechanism.
The adjusting motor (electric motor) for the adjusting mechanism, which adjusting motor is mounted fixedly on the internal combustion engine, makes a radial balancing clutch necessary between the motor shaft of the electric motor and the input shaft of the adjusting mechanism, as is shown in DE 10 2005 018 956 A1.
DE 103 52 255 A1 discloses a camshaft adjuster having an adjusting drive which is configured as a three-shaft gear mechanism. The electric motor is arranged spatially separately from the adjusting shaft of the adjusting mechanism; the adjusting moment is transmitted by a flexible shaft. One variant provides that the motor and the motor shaft lie parallel to the camshaft and the adjusting moment is introduced via a secondary drive which is configured as a chain drive, belt drive or the like.